The present invention relates generally to computer networks and more particularly to a line powered control and switching device for selectively coupling a remote terminal at a remote location through modems and a telephone line to a system console, the TTO/TTI port and ALM/IAC port of a host computer and to a user terminal for remote diagnosis of hardware and software problems and which provides different degrees of access of the remote terminal and a variety of operating modes.
It is not uncommon for computer systems users to experience hardware or operational software problems in the day-to-day use of their equipment. In some instances the problems are such that they can be diagnosed and/or corrected by on-site personnel; however, in most cases the user does not possess the technical skills needed to properly diagnose and then correct the fault. When this occurs it is generally necessary to obtain outside assistance from a technical expert at a support center.
In the past, attempts have been made to diagnose and correct operational problems by calling the support center over a telephone and describing to a technical expert at a support center what appears to be the particular problem. This technique has not proven to be very successful, mainly because of the inability of the person at the user site to accurately describe the problem and/or what he is actually observing on his display terminal. Furthermore, the technique does not enable the technical expert to actually control the operations of the computer at the user site.
Another technique that has been employed in the past has involved connecting the CPU and the display terminal at the user site to an acoustic coupler through a double throw switch. When the switch is placed in one position the CPU is connected to the display terminal and is operable with the display terminal as a user site computer. When the switch is placed in the other position the CPU is connected to the acoustic coupler. Using this arrangement it is possible to connect the CPU to either the display terminal at the user site or through a telephone link and second acoustic coupler to a display terminal at the support center. The basic problem with this technique is that although it allows either the display terminals at the user site or the display terminal at the support center to be connected to the CPU it does not allow both display terminals to be connected to and be in communication with the CPU at the same time. Thus, it does not enable a person at the support center to monitor operations of the display terminal at the user site or the operator at the user site to observe the communications between the display terminal at the support center and the CPU. In addition, once the telephone instruments at each location are inserted into their respective acoustic couplers there is no way for the person at one location to signal to the person at the other location to remove the telephone instrument from the acoustic coupler if the person wants to reestablish voice communications or return to the original operating mode.
In U.S. Pat. No. 4,356,545 to K. J. West there is described an apparatus for monitoring and/or controlling the operations of a computer at a user site from a support center over a telephone line, the computer at the user site including a central processing unit (CPU) and a display terminal. The apparatus includes a telephone instrument at each location connected to the telephone line, a display terminal connected to an acoustic coupler at the support center and a control and switching device at the user site connected to the CPU, to the display terminal at the user site and to an acoustic coupler. When a link is established between the acoustic coupler at the support center and the acoustic coupler at the user site over the telephone line, the display terminal at the support center is operable with the display terminal at the user site in either an on-line mode or a conversational mode. In the on-line mode, either display terminal can input to the CPU and the output from the CPU is displayed at both display terminals. In the conversational mode, the CPU is disengaged and inputs from either display terminal are displayed at both display terminals. In the absence of the link, the display terminal at the user site is operable with the CPU through the control and switching device.
In copending U.S. patent application Ser. No. 528,566 filed on Aug. 31, 1983 and assigned to the assignee of this application there is disclosed a control and switching device which links a remote terminal by modems over telephone lines to a local central processing unit (CPU) and a local computer console terminal. The device, which is coupled by separate lines to the modem at the local site, the local console and the TTY and ASYNC ports of the CPU, includes a microprocessor, a memory, logic circuits and a switch assembly. The switch assembly includes first, second and third switches which are interlocked and which allow three different levels of remote access of the remote terminal. When the first switch is depressed, the device is powered down, the remote terminal has no access to either the TTY or ASYNC ports of the CPU and the local console is hardwired through the device to the TTY port of the CPU. When the second switch is depressed, the local console is hardwired to the TTY port of the CPU and the remote terminal is electrically connected to the ASYNC port of the CPU. When the third switch is depressed, the local console and the remote terminal both have access to either the TTY port or the ASYNC port of the CPU. A variety of firmware commands stored in the device, some of which may be applied by the local console and some by the remote terminal, depending on which switch is depressed, provide a number of different operating modes, the modes including a conversation mode wherein the CPU is locked out and the local console and remote terminal can communicate directly with each level.
It is an object of this invention to provide a new and improved control and switching device for allowing a remote terminal at a remote site to access a local system at a local site through modems over a telephone line.
It is another object of this invention to provide a control and switching device as described above which enables the remote terminal to access the local system for diagnosis and fault determination of hardware and software problems.
It is still another object of this invention to provide a control and switching device as described above which is microprocessor based.
It is yet still another object of this invention to provide a control and switching device as described above which provides multiple levels of security.
It is a further object of this invention to provide a control and switching device as described above which does not reduce the number of user terminals that may be connected to the computer system.
It is another object of this invention to provide a control and switching device as described above which provides multiple levels of access.
It is still another object of this invention to provide a control and switching device which allows a remote terminal to access a local CPU either as a user or for diagnostic/maintenance purposes.
It is a further object of this invention to provide a control and switching device as described above wherein either the local computer console terminal or the remote terminal can be made master.
It is another object of this invention to provide a control and switching device as described above which is completely under control of the local console operator.
It is still another object of this invention to provide a control and switching device as described above which is easy to install.